Specifications

17-2
Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
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Chapter 17 Configuring Voice VLAN
Configuring Voice VLAN
Figure 17-1 shows one way to connect a Cisco 7960 IP Phone.
Figure 17-1 Cisco 7960 IP Phone Connected to a Switch
When the IP Phone connects to the switch, the access port (PC-to-telehone jack) of the IP phone can
connect to a PC. Packets to and from the PC and to or from the IP phone share the same physical link to
the switch and the same switch port. For deployment examples that use voice VLANs, refer to the
“Network Configuration Examples” section on page 1-8.
Configuring Voice VLAN
This section describes how to configure voice VLAN on access ports. It contains this configuration
information:
• Default Voice VLAN Configuration, page 17-2
• Voice VLAN Configuration Guidelines, page 17-3
• Configuring a Port to Connect to a Cisco 7960 IP Phone, page 17-3
Default Voice VLAN Configuration
The voice VLAN feature is disabled by default.
When the voice VLAN feature is enabled, all untagged traffic is sent according to the default CoS
priority of the port.
The default CoS value is 0 for incoming traffic.
The CoS value is not trusted for 802.1P or 802.1Q tagged traffic.
The IP Phone overrides the priority of all incoming traffic (tagged and untagged) and sets the CoS value
to 0.
Note In software releases earlier than Release 12.1(13)EA1, the CoS value is trusted for all 802.1P or 802.1Q
tagged traffic, and the IP Phone does not override the priority of the incoming traffic.
3-port
switch
P1 P3
P2
Access
port
Cisco IP Phone 7960
PC
Catalyst 2950 or
3550 switch
74710
Phone
ASIC